13 Mistakes Everyone Makes When Cooking Frozen Fish
Thanks to home freezers, we all spend far less time at the grocery store than our great-grandparents did. That, and the modern world lets us enjoy good-quality fish without investing in coastal real estate; if you want to talk about technology that was a good idea, you want to talk about the technology that makes it possible to have a decent shrimp dish while admiring the Nebraska plains or the view from the Rocky Mountains.
It might seem counterintuitive, but the "fresh" fish you buy may have been frozen first — and conversely, frozen fish is often more fresh than the "fresh" fish in the grocery store. That's thanks to the heroic work of the fishers who flash-freeze their catches, and thanks to the less heroic work of the fishmongers who let unfrozen fish sit for days on the seafood counter. We're not saying to never buy fresh fish. We're just saying that you don't need to be skittish about buying frozen. Cooking frozen fish comes with its own set of techniques, though, and it's important to avoid these common mistakes.
1. Mistake: Buying the wrong type of fish
When buying fresh fish, there are location-specific factors to take into account, like regionality and seasonality. Do you live near a lake, but not an ocean? Then maybe you opt for perch over tuna, if you're buying fresh. Frozen fish takes some of those variables out of the equation, but you'll still want to be aware of how the fish will behave culinarily. "Fish," after all, is a catchall term for a bunch of very different types of seafood — salmon is distinct from tilapia, is distinct from tuna steaks, is distinct from canned tuna, and so on. So a little knowledge and forethought of what exactly you want to cook goes a long way here.
Certain fish, like tuna and yellowtail, are simply too oily to handle being frozen well. We'll get into the cooking method-related reasons why later, but suffice to say that the mixture of oily fish and the moisture leftover from freezing do not always mix. The key to buying the best frozen fish is to choose fish with few bones and lean fillets. Cod, haddock, and salmon are excellent options to buy frozen, as is Chilean sea bass.
2. Mistake: Buying fish that isn't frozen at the right time
Frozen fish can be every bit as fresh, if not fresher, than what is sold as fresh, and with that assertion comes a big, flashing neon sign of a caveat — the fish should be flash-frozen, either while the catch is still at sea or immediately on reaching the shore. Flash-freezing means making the fish very cold, very fast, and thus preventing the development of quality-destroying ice crystals that form when fish is frozen in slower, more conventional ways. This is freezing at peak freshness, and that's essential for fish. Especially if you, the consumer, live in a place that requires the fish to have spent time traveling to your grocery shelves.
On the flip side, be wary of fish marketed in-store as "fresh." The benefit of freezing fish is that peak freshness is locked in. If the fish on the store shelves isn't frozen, it may have been previously frozen, then thawed to appear fresh. There isn't really a good way to know how much time the fish has spent at suboptimal temperatures. Look out for any labels that read "thawed from previously frozen" and consider avoiding those products.
3. Mistake: Trying to sear from frozen
Once you've reeled in your supermarket catch, you've got to cook the thing. Luckily, there's yet another benefit of frozen fish: You don't necessarily have to worry about that pesky thawing step. Put one way, you can save a little time. Put another, you're not totally in a bind if it's time to cook dinner and you've only just now realized that you forgot to take the fish out of the freezer — fish can cook completely from frozen! However, we must warn you that the door is closed on one beloved cooking method if you do this.
Searing — that high-heat cooking that results in beautifully blackened catfish, for instance — is a no-go for a fillet that still rattles like a snare drum if you drop it on the counter. The fish will have a buildup of unfrozen moisture. If all of that ice suddenly starts melting when in a high-heat pan, the results in the pan aren't going to be too pretty. Instead of a nice sear, you end up with a soggy fish. Make sure your fish is carefully thawed and patted dry before adding it to high heat.
4. Mistake: Not thawing your fish properly
Carefully thawing fish is extremely important. Thawing is simple in principle: Take the fillet out of freezing temperature, wait until it isn't hard as a rock, then cook. Turns out, a few things can go seriously wrong with that. The best way to thaw frozen fish, is simply to leave the fish in the fridge for at least 10 hours, depending on the thickness of the cut. Usually, this means thawing overnight for dinner the next evening.
That said, we get it: Sometimes you forget, something comes up, or plans change. Don't panic. If you're pressed for time, you can defrost fish by submerging it in cold water, but take note that this will affect the fish's texture. However you thaw, make sure to remove the fish from any vacuum-sealed packaging. If your fish has been frozen in a vacuum-sealed package, thawing while still in that plastic can potentially cause botulism, according to the FDA. C. botulinum bacteria does really well in low-oxygen environments — like vacuum-sealed packaging — provided the temperature is at 38 degrees Fahrenheit or higher. The average fridge is set between 37 and 40 degrees, so make sure to either remove the fish from its packaging entirely, or at least poke a few holes in the plastic.
5. Mistake: Accidentally cooking the fish during the thawing process
How much time your not-yet-cooked fish spends at what temperatures is crucial to pay attention to. Of course, if you thaw your fish overnight in the fridge, you don't have to worry about this as much, but if you're thawing in a hurry? Be mindful. Fish is a sensitive food. If certain temperatures are reached, the cooking process starts. If that process isn't immediately continued and/or finished quickly, your dinner can go from "exciting" to "inedible for safety reasons" before you have time to squeeze a lemon.
This is mostly a concern for microwave thawing, which the U.S. Food Safety and Inspection Service says can be done as long as the fish is cooked immediately after thawing. The FSIS also warns not to thaw food "... in a garage, basement, car, dishwasher or plastic garbage bag; out on the kitchen counter, outdoors or on the porch," for the same microbe-related reasons. Remember: Freezing food doesn't kill microbes, instead only making them dormant. Killing the microbes is what cooking does.
6. Mistake: Not patting your fish dry
Getting rid of all that excess moisture that builds up from freezing is worth doing, if you're not cooking from frozen. However, defrosting by itself is not enough. The outside of the fish should be dry, to prevent it from getting bogged down in its own juices during cooking. This is a step you shouldn't skip with a lot of different kinds of meat, but it matters especially with fish. Juices leaking into the pan will carry away a lot of seasonings with them, leaving behind a more bland fish than what you thought you were getting — that's why patting dry after thawing is so important.
It doesn't take much to dry off your defrosted fish. Just a paper towel or two gently pressed all over will do. Gentleness is key! You don't want to accidentally mangle your fish or mess with its texture. Once the exterior is dry, you can add oil and seasoning and proceed with cooking. Alternatively, you can marinade your fish which, yes, is re-introducing moisture. The difference is that a marinade has flavor, whereas melting ice crystals from the freezing process are decidedly less exciting to your taste buds. You'll still want to pat the fish dry before adding it to your marinade.
7. Mistake: Over-marinating your fish
If you're really planning ahead, a marinade is a fantastic way to kick your fish up a notch. Marinating doesn't have to take much, either — something as simple as olive oil, lemon juice, garlic, and a couple of herbs and spices goes a long way. But there's a marinating mistake that it's essential to avoid, lest your fish disintegrate like cotton candy dropped in a puddle.
Just be careful with any marinade involving citrus, like lemon, lime, and orange juices. Fruit juice enzymes make for wonderfully tender meat, but there's a limit. The acidity in these ingredients can start to cook raw fish. In fact, this is the main principle behind how ceviche is "cooked." Thawed fish will absorb marinades within 15 minutes, and you should not marinade for longer. Nor should you thaw your fish in marinade. The end results of doing that is more like something out of a H.P. Lovecraft story than a McCormick and Smchick's cookbook.
8. Mistake: Cooking with a cold pan
Forgetting to preheat your pan is a classic mistake for beginner cooks. Speaking generally, for meat, you almost never want to start with a cold pan or cold oil. Think of it like using the oven. You don't dial up the temperature, then throw your food in before the gas turns on. Oil-greased pans are the same way. The preheating process is relatively gradual, and the food you're cooking needs to be around for it about as much as an average driver needs to be involved at the automobile factory.
Not preheating your pan means the fish is coming up to temperature at the same time everything else in the cooking environment. Any oil (or butter, stock, or curry paste) will grease up the fillet instead of frying it. Not only that, a cold pan will ensure all of the moisture in the fish seeps out. By the time you're done, what you're left with is mushy, unappetizing fish and a lot of juice in the pan.
9. Mistake: Not getting creative with your cooking methods
If all you know is pan frying or baking fish, allow frozen fish to be your excuse to branch out. Frozen fish is great for fish stew or curry, or something where the fish itself isn't the star, like tacos. Whether cooking from frozen, thawing before you cook, or thawing and then marinating, keeping your texture consistent can sometimes be a challenge.
Professional chefs have their own tips for working with frozen fish, such as opting for baking, since that cooks the fish less harshly and more evenly than pan-frying. Frozen fish can also work excellently for soups or stews. Alternatively, if it's available to you, a sous vide water bath does wonders for frozen fish, giving a way to accurately control the temperature during cooking. The end result is a perfectly cooked fish throughout, with none of that cooked-on-the-outside-raw-on-the-inside stuff of your nightmares.
10. Mistake: Using the wrong method for oily fish
Once again, knowing what kind of fish you're preparing is imperative; all of those little swimmers behave differently to one another. It's not hard to mess up a dish if you go in all cavalier, flipping and frying without a care in the world. Oily fish — like salmon, trout, mackerel, or tuna — can get as soggy as socks in the rain if you're not careful. Calling for pizza delivery because the cook bungled the works might seem like a fun detour in TV commercials, but it's not a great feeling if you're the cook.
This mostly applies to cooking oily fish from frozen. High heat, when cooking from frozen, will leak out excess moisture faster than an outdoor hockey rink at the first blush of spring. Choose a preparation like poaching, baking, or currying when making these from frozen. These methods ensure gentle, even cooking, which lets that trout lounge delicately on your plate, rather than crumbling.
11. Mistake: Not using higher heat for for white fish
White fish, like cod, monkfish, halibut, or sea bream, respond very well to high heat. We still advise against searing, but a high temperature is great for getting that wonderful textural difference of blackened on the outside and flaky on the inside. You know, the way you'd want your fish cooked if you were being cooked for by an old fisherman who lived in a riverside shack. This style is great for sandwiches, tacos, and many other dishes where white fish is one of many ingredients.
Generally a little firmer than its oily counterparts, white fish cooked from frozen can stand up to grilling or pan-frying — provided you're fastidious about removing excess water. Even if you're pulling these straight from the freezer to toss in the pan, a touch of gentle thawing will still yield better results. Don't forget the all-important step of patting the fillet dry with paper towels. Then, you can go ahead and use higher heat to cook your haddock or tilapia.
12. Mistake: Not soaking the fish in a milk bath to remove odors and add flavor
"Wait a second," you might be thinking, "what?" It's fair to wonder how milk got into the equation. It's true, though: Milk can really add a lot to any fish dish, and we're not talking about the coconut milk in curry, either. No, we're talking about whole or 2% cow's milk (emphatically avoiding 1% or skim, as they don't work quite right for this application).
Now, milk isn't exactly necessary for a perfectly cooked frozen fish, but it can help eliminate some fishy smells and add a pleasant, slightly sweet flavor. Simply defrost the frozen fish by placing it in a milk bath in the fridge for up to eight hours before cooking. As long as it's in the refrigerator, it's fine to thaw it this way. Just don't leave fish in a bowl of milk out on the counter, or any other environment besides the refrigerator, for reasons that should be obvious. If you fish is already thawed, it can still go for a milk bath for a 10-20 minute soak. Either way, a chilled milk bath is definitely a good way to kick your fish up a notch. Not only that, but a little milk on the fillet will help brown during cooking. You still want to pat the excess milk off of the fish, but leaving a little milk helps the color.
13. Mistake: Keeping fish in the freezer for too long
If you need frozen fish demystified a bit, hopefully this article will help. Knowing how to properly prepare frozen fish opens up all sorts of seafood-related possibilities, and lets you stock up for whenever you need it. For one thing, you don't necessarily have to make "salmon night" and "grocery store day" the same 24-hour period. For another thing, you can buy frozen fish in bulk, which can often be a money-saving move. Go ahead and pick up that bag of vacuum-sealed, flash-frozen tilapia. Have fish tacos next Thursday — and be careful to avoid these easy fish taco mistakes when you do.
One important thing to remember, though, is not to buy that fish in bulk and then forget that it's sitting in your freezer. According to FoodSafety.gov, no fish is good for longer than eight months in the freezer. Fatty fish, like salmon, mackerel, or catfish, only last about three months, tops. Leaner fish, like flounder, halibut, sole, or trout can go a bit longer, lasting for up to eight months. No matter what, if you're able to do so, it's good practice to eat things relatively soon after putting them in the freezer. The ability to freeze food might be a modern miracle, but it's not literally magic. Try not to let that tilapia get buried under your ice cream.